The present invention relates to an information device for on-vehicle use.
In the prior art, with an information device for on-vehicle use such as, for example, a car navigation device, when the ignition key of the vehicle is turned OFF (i.e. has been rotated from the ACC position to the OFF position), all the power which is being supplied to the car navigation device has been turned OFF after certain predetermined required information has been saved in non volatile memory or the like. Next, when the ignition key is turned ON (i.e. has been rotated from the OFF position to the ACC position or to the ON position), the power supply to the car navigation device is turned ON, and, after the previous required information has been read out from the non volatile memory and a predetermined setup procedure has been performed based upon this information, the car navigation device is made available for use.
However, since a certain time period is required after the power supply has been turned ON for the reading out from the non volatile memory and for the subsequent setup, it has been necessary to wait for a considerable waiting period until the car navigation device becomes available for use.
The objective of the present invention is to propose an information device for on-vehicle use which includes a more suitable power control device, and which is made so as to be able to be used promptly after the power supply has been turned ON, in its state before the power supply was turned OFF.
In order to attain the above objective, an information device for on-vehicle use, comprises: a CPU which is capable of normal operation and of standby operation which achieves low power consumption; a first power supply for use during the normal operation of the CPU; a second power supply for use during the standby operation of the CPU; and a power control device which performs ON-OFF control of the first power supply and the second power supply. And the CPU outputs a first signal to the power control device when the CPU transits from the normal operation to the standby operation; the power control device outputs a second signal to the second power supply which turns the second power supply ON when the first signal has been inputted from the CPU, and outputs a third signal to the first power supply which turns the first power supply OFF after a predetermined time period has elapsed after the output of the second signal; the CPU outputs a fourth signal to the power control device when the CPU transits from the standby operation to the normal operation; and the power control device outputs a fifth signal to the first power supply which turns the first power supply ON when the fourth signal has been inputted from the CPU, and outputs a sixth signal to the second power supply which turns the second power supply OFF after a predetermined time period has elapsed after the output of the fifth signal.
In this information device for on-vehicle use, it is preferred that: a DRAM which is employed in the normal operation of the CPU and a third power supply which supplies power to the DRAM are further provided; and when the CPU transits from the normal operation to the standby operation, the third power supply continues to supply power to the DRAM.
Also, it is preferred that: there is further provided an ON-OFF detection device which detects a signal for turning the information device for on-vehicle use ON and OFF in association with operation of an ignition key of a vehicle; when the ON-OFF detection device has detected a signal to turn the information device for on-vehicle use OFF, the ON-OFF detection device notifies the CPU to an effect that the ON-OFF detection device has detected the signal to turn the information device for on-vehicle use OFF; and the CPU transits to the standby operation after having executed a predetermined procedure for standby. In this case, it is preferred that: when the ON-OFF detection device has detected a signal to turn the information device for on-vehicle use OFF directly before rotation of a starter motor of the vehicle, the ON-OFF detection device notifies the CPU to an effect that the ON-OFF detection device has detected the signal to turn the information device for on-vehicle use OFF directly before rotation of the starter motor of the vehicle; and the CPU transits to the standby operation after only a portion of the procedure for standby has been executed, so that the procedure for standby is completed before starting of rotation of the starter motor of the vehicle.